title: H-NS can facilitate specific DNA-binding by RNA polymerase in AT-rich gene regulatory regions.
abstract: Extremely AT-rich DNA sequences present a challenging template for specific recognition by RNA polymerase. In bacteria, this is because the promoter -10 hexamer, the major DNA element recognised by RNA polymerase, is itself AT-rich. We show that Histone-like Nucleoid Structuring (H-NS) protein can facilitate correct recognition of a promoter by RNA polymerase in AT-rich gene regulatory regions. Thus, at the Escherichia coli ehxCABD operon, RNA polymerase is unable to distinguish between the promoter -10 element and similar overlapping sequences. This problem is resolved in native nucleoprotein because the overlapping sequences are masked by H-NS. Our work provides mechanistic insight into nucleoprotein structure and its effect on protein-DNA interactions in prokaryotic cells.
authors.affiliation: Institute for Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, USA.
authors.forename: Shivani S
authors.initials: SS
authors.lastname: Singh
authors.forename: David C
authors.initials: DC
authors.lastname: Grainger
mesh_terms: D020856:AT Rich Sequence / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D036781:Fimbriae Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D006657:Histones / Q000235:genetics; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C529458:FimG protein, E coli; D006657:Histones; D036781:Fimbriae Proteins; D012321:DNA-Directed RNA Polymerases